Patients who suffer from respiratory ailments including chronic obstructive pulmonary disease, asthma, bronchitis, tuberculosis, or other disorder or condition that causes respiratory distress, often self-administer medication to treat symptoms for those ailments.
Presently, many patients attempt delivery of medications to the respiratory system through hand-held metered dose inhalers (MDI) and dry powder inhalers (DPI). Small volume nebulizers (SVN) may also be used. An MDI is a device that helps deliver a specific amount of medication to the lungs, usually by supplying a short burst of aerosolized medicine that is inhaled by the patient. A typical MDI consists of a canister and an actuator (or mouthpiece). The canister itself consists of a metering dose valve with an actuating stem. The medication typically resides within the canister and is made up of the drug, a liquefied gas propellant and, in many cases, stabilizing excipient. Once assembled, the patient then uses the inhaler by pressing down on the top of the canister, with their thumb supporting the lower portion of the actuator. Actuation of the device releases a single metered dose of liquid propellant that contains the medication. Breakup of the volatile propellant into droplets, followed by rapid evaporation of these droplets, results in an aerosol consisting of micrometer-sized medication particles that are then breathed into the lungs. Other MDI's are configured to be charged by twisting a cylinder that charges the device. A button on a side of the cylinder is depressed by the user which results in a timed release of nebulized or aerosolized medication for inhalation by the patient.
DPI's involve micronized powder often packaged in single dose quantities in blisters or gel capsules containing the powdered medication to be drawn into the lungs by the user's own breath. These systems tend to be more expensive than the MDI, and patients with severely compromised lung function, such as occurs during an asthma attack, may find it difficult to generate enough airflow for satisfactory performance.
While used widely for the treatment of respiratory distress, treatment protocols using MDI's and DPI's ignore the physiological state of patients suffering from respiratory distress. That is, generally speaking, many patients presenting symptoms related to respiratory distress suffer from closed or inflamed alveoli. It is the inflammation of the airways within the lungs of the patient that causes discomfort and other symptoms related to their respiratory distress. Unfortunately, common treatment techniques related to MDI and DPI use, deliver medication to inflamed and non-inflamed airways alike. The desired physiological response to the administered medications (i.e., the opening or reduced inflammation of the airways, etc.) is delayed as the medication is absorbed into the bloodstream and thereafter delivered to the closed or inflamed airways. Moreover, use of MDI's or DPI's can be difficult to administer to very young or very old patients or others with decreased or low dexterity. For example, a patient suffering from an acute asthmatic attack may have a difficult time taking a deep enough breath to move an aerosol from an MDI down through the patients airway. A need exists, therefore, for improved systems and methods for lung recruitment and more efficient delivery of medication to the lung.